« السابقةمتابعة »
would be drowned or burnt along with the rest of the world !”
“ O yes, father,” resumed John; “ I know that well enough, and I only talked of the water, as just such another silly story as Peggy's about fire. But very sensible people really say that the Comet will do nothing but sink wages, and blight the crops, and breed famine and sickness, and make every body miserable; and, besides all that, that it will bring war, and spread trouble all over the country: and that is the reason why I think it a good thing that we are going away!”
“Depend upon it, my good Tom," interrupted Mr. Gubbins, “that the whole of what you have said is just as foolish, or pretty nearly so, as either of the stories about fire and water; so that I won't have my pretty little Peggy's nice story, about the world on fire, too hastily put aside, only to make way for others about war and famine! The appearance of a Comet, my good Tom, would most likely give occasion to more of these stories, but that it happens so seldom, and so irregularly (as far as we have yet been able to observe), and is therefore so little understood, both as to its causes and consequences.”
“But tell us, Master Ephraim,” said Farmer Mowbray, “ what you really think yourself about the consequences of the appearance of a Comet? Mind, I don't ask you, now, what you think about the causes, or even about the nature, of those blazing stars.'”.
“Then,” replied Mr. Gubbins,“ there is but one thing which seems to me certain; and that is, that the consequence of the approach of a Comet, other circumstances equal, must be an increase of the warmth of the season. We derive heat from the moon, the planets, and even the fixed stars, as well as from the sun; and, no doubt, the presence of a Comet in our part of the heavens must increase the heat of our atmosphere. But this increase of heat, in some seasons and circumstances, may happen to be an evil; and I should add, that the Comel's beat, by increasing evaporation, may have its effect upon the quantity of rain : and thus far, a Comet may either threaten or comfort us with the promise of either fire or water. During a considerable cometary appearance which I remember, there was no other consequence or accompaniment, that I am even yet aware of, than the production of a remarkably warm and fine autumn.”
“Do they not say, Mr. Gubbins,” inquired the farmer's wife, “ that we are to have two Comets this year?
“ They do,” answered Mr. Gubbins; “ one, which they call the Comet of Encke (that is, of the astronomer of that name, who discovered its former appearance); but which is not expected, however, to be seen from this Northern Hemisphere of the earth; and another, called, for a reason like the former, the Comet of Biela, and which, it is true, is expected, from the calculations, to make, at its nearest point, an extraordinarily near approach, not to the earth itself, but only to its orbit, or road upon which it travels; and even this no nearer than fifty millions of miles : and, to form some idea of the extent of that distance (though, at last, a poor one), you may recollect, that the whole diameter of the earth (or length of a line drawn through the globe, from one of its sides to the other), is reckoned at no more than eight thousand miles, or less, by a fifth, than the hundredth part of a million ; or, that this distance of fifty millions of miles, stretched
out into universal space, is equal to eight millions two hundred and fifty thousand times the whole length or breadth of the earth! It is true that, after all, we may be said to form no idea whatever of such distances, intervals, or spaces, because they can scarcely be compared with any thing that we know; and it is also true, that consequently we are in some degree unable to judge of the distance at which a Comet may or may not exercise an influence upon the temperature of our atmosphere and earth; but, at least, this computation of distance may serve to remove every fear that the Comet of Biela will touch our planet. You see that, when it is nearest to the earth, it will be distant almost eight millions and a quarter of times the length of the whole earth itself, from one pole to the other, as the crow would fly, or a ship sail !”
“By the way,” continued Mr. Gubbins, “(and the knowledge of the frequency and regularity of Comets is a great remover of our terrors) it is at present understood, that upon an average of years, there are two cometary appearances in our system in each year; though for want of earlier observation and instruments, only five hundred are recorded since the Christian era; or, little more than one-fourth of the estimated number of so long a period.”
“But the times of their appearance,” said Mrs. Mowbray, “ are still thought uncertain?”
“Quite so," answered Mr. Gubbins; "unless, indeed, there should be reason for the calculation which has been attempted concerning the most remarkable Comet of modern history; that of the year 1680.”
“ Pray,” said Mrs. Mowbray, “what is the calculation?"
“ There was a remarkable Comet,” returned her informant, “ in the year of the assassination of Julius Cæsar; that is, in the year 43 before the Christian era. There was another in the year 531 of that era; a third in the year 1106; and a fourth, as I have said, in the year 1680. Now, from the year 43 before the Christian era, to the year 531 after it, is five hundred and seventy-four years; from the year 531, to the year 1106, is five hundred and seventy-five years; and from the year 1106 to the year 1680, is five hundred and seventy-four years: so that, supposing all these appearances to have been reappearances of the same Comet, we should thus ascertain, that one, and that the largest Comet of our system, or that which, in the course of its revolution, approaches the nearest to us, and has always been the especial subject of alarm,that this Comet performs that revolution, or goes from us and returns to us, once in about five hundred and seventy-five years; a period nineteen times as long as that of the revolution of the planet Saturn, and nearly seven times that of the great and distant planet Uranus, or Georgium Sidus; a period, in short, which, if admitted, leaves us no room to expect the return of the Comet of 1680 (sometimes called Halley's Comet, and that which was the occasion of the bringing forth the two wild theories of Whiston and Halley respectively), nor of that of any other very remarkable or alarming Comet (so to call it) till about the year 2255; and, for a degree of further present comfort, it may be as well, before we go on, to make mention, that the Comet of Encke, which according to elaborate calculations, is said to be the particular Comet likely, after an almost endless succession of revolutions (always coming nearer and nearer), to make this fatal visit to our earth;—this
most terrible visit of all visits,—the only one of the kind, the date of which astronomers are in any degree able to anticipate, and-as the equal result of the same calculations, this cannot happen, as they themselves say, before the end of the next two hundred and nineteen millions of years; a distant evil, and which itself is never likely to arrive, if the calculation I have mentioned is well-founded; and which would prove, from the uniformity of the periods of cometary evolutions, that they keep uniformly to their ancient, though eccentric orbits, neither expanding nor contracting their limits, nor changing their direction! But it may possibly, in the meantime, be worth our while to note, that this assumed average cometary period, of five hundred and seventy-five years, differs but little from the famous Babylonish cycle of six hundred !-I vouch not for the truth of any of the calculations; but, supposing that this last Comet, or that one, or that several of the Comets of our system, make revolutions of so great a length of time, while, in reality, two Comets, upon an average, become annually visible, how many in number must not the Comets of our system be!”
“They must far out-number,” said one of the company," the whole of all our planets !"
“ Very far, indeed,” added Mr. Gubbins; “even at the most moderate reckoning; and notwithstanding that, at present, we reckon eleven planets, instead of the five of even modern astronomy, and the seven of ancient; six having been added to the catalogue since the year 1780*. The supposition, in the
* Herschel's discovery, or that of his sister, of the first of these six, was made upon the 18th of March, 1781.